[tiger.ml.git] / compiler / src / lib / tiger / tiger_semant.ml

module List = ListLabels

module A         = Tiger_absyn
module Env       = Tiger_env
module E         = Tiger_error
module Translate = Tiger_translate
module Type      = Tiger_env_type
module Value     = Tiger_env_value

(* The only reason for having this seemingly-superfluous inner module is to
 * have this nice signature as a summary of what each function does. *)
module Semant : sig
  type expty =
    { exp : Translate.exp
    ; ty  : Type.t
    }

  (* Violating normal naming convention just to make it easier to follow
   * Appel's
   *)
  val transExp : env:Env.t -> A.exp -> expty
  val transVar : env:Env.t -> A.var -> expty
  val transDec : env:Env.t -> A.dec -> Env.t
  val transTy  : env:Env.t -> A.ty  -> Type.t  (* needs only type env *)
end = struct
  type expty =
    { exp : Translate.exp
    ; ty  : Type.t
    }

  let unimplemented () =
    failwith "unimplemented"

  let return ty     = {exp = (); ty}
  let return_unit   = return Type.Unit
  let return_nil    = return Type.Nil
  let return_int    = return Type.Int
  let return_string = return Type.String

  let env_get_typ ~sym ~env ~pos : Type.t =
    match Env.get_typ env sym with
    | Some ty -> ty
    | None    -> E.raise (E.Unknown_type {ty_id=sym; pos})

  let env_get_val ~sym ~env ~pos : Value.t =
    match Env.get_val env sym with
    | Some ty -> ty
    | None    -> E.raise (E.Unknown_id {id=sym; pos})

  let check_same {exp=_; ty=ty_left} {exp=_; ty=ty_right} ~pos : unit =
    if Type.is_equal ty_left ty_right then
      ()
    else
      E.raise (E.Wrong_type {expected=ty_left; given=ty_right; pos})

  let check_int expty ~pos : unit =
    check_same {exp=(); ty=Type.Int} expty ~pos

  (* TODO: actual_ty *)

  let rec transExp ~env exp =
    let rec trexp exp =
      (match exp with
      | A.NilExp ->
          return_nil
      | A.IntExp _ ->
          return_int
      | A.StringExp {string=_; _} ->
          return_string
      | A.CallExp {func; args; pos} ->
          (match env_get_val ~sym:func ~env ~pos with
          | Value.Fun {formals; result} ->
              List.iter2 formals args ~f:(fun ty_expected exp_given ->
                check_same {exp=(); ty = ty_expected} (trexp exp_given) ~pos;
              );
              return result
          | Value.Var _ ->
              E.raise (E.Id_not_a_function {id=func; pos})
          )
      | A.OpExp {oper; left; right; pos} ->
          trop oper ~left ~right ~pos
      | A.RecordExp {fields=field_exps; typ; pos} ->
          let ty = env_get_typ ~sym:typ ~env ~pos in
          Type.if_record
            ty
            ~f:(fun field_tys ->
              List.iter field_exps ~f:(fun (field, exp, pos) ->
                (match List.assoc_opt field field_tys with
                | Some field_ty ->
                    check_same {exp=(); ty=field_ty} (trexp exp) ~pos
                | None ->
                    E.raise
                      (E.No_such_field_in_record {field; record=ty; pos})
                )
              )
            )
            ~otherwise:(fun () ->
              E.raise (E.Wrong_type_used_as_record {ty_id=typ; ty; pos})
            );
          return ty
      | A.SeqExp exps ->
          (* Ignoring value because we only care if a type-checking exception
           * is raised in one of trexp calls: *)
          List.iter exps ~f:(fun (exp, _) -> ignore (trexp exp));
          return_unit
      | A.AssignExp {var; exp; pos} ->
          check_same (trvar var) (trexp exp) ~pos;
          (* TODO: Add var->exp to val env? *)
          return_unit
      | A.IfExp {test; then'; else'; pos} ->
          (* test : must be int, because we have no bool *)
          (* then : must equal else *)
          (* else : must equal then or be None *)
          check_int (trexp test) ~pos;
          (match (trexp then', else') with
          | expty_then, None ->
              expty_then
          | expty_then, Some else' ->
              let expty_else = trexp else' in
              check_same expty_then expty_else ~pos;
              expty_then
          )
      | A.WhileExp {test; body; pos} ->
          (* test : must be int, because we have no bool *)
          check_int (trexp test) ~pos;
          ignore (trexp body);  (* Only care if a type-error is raised *)
          return_unit
      | A.ForExp {var; lo; hi; body; pos; escape=_} ->
          check_int (trexp lo) ~pos;
          check_int (trexp hi) ~pos;
          (* Only care if a type-error is raised *)
          ignore (transExp ~env:(Env.set_typ env var Type.Int) body);
          return_unit
      | A.BreakExp _ ->
          return_unit
      | A.LetExp {decs; body; pos=_} ->
          (* (1) decs augment env *)
          (* (2) body checked against the new env *)
          let env =
            List.fold_left decs ~init:env ~f:(fun env dec -> transDec dec ~env)
          in
          transExp body ~env
      | A.ArrayExp {typ; size; init; pos} ->
          check_int (trexp size) ~pos;
          let ty = env_get_typ ~sym:typ ~env ~pos in
          Type.if_array
            ty
            ~f:(fun ty_elements ->
              check_same {exp=(); ty=ty_elements} (trexp init) ~pos
            )
            ~otherwise:(fun () ->
              E.raise (E.Wrong_type_used_as_array {ty_id=typ; ty; pos})
            );
          return ty
      | A.VarExp var ->
          trvar var
      )
    and trvar =
      (function
      | A.SimpleVar {symbol=sym; pos} ->
          (match env_get_val ~sym ~env ~pos with
          | Value.Fun _    -> E.raise (E.Id_is_a_function {id=sym; pos})
          | Value.Var {ty} -> return ty
          )
      | A.FieldVar {var; symbol; pos} ->
          let {exp=_; ty} = trvar var in
          Type.if_record
            ty
            ~f:(fun fields ->
              (match List.assoc_opt symbol fields with
              | None ->
                  E.raise
                    (E.No_such_field_in_record {field=symbol; record=ty; pos})
              | Some ty ->
                  return ty
              )
            )
            ~otherwise:(fun () -> E.raise (E.Exp_not_a_record {ty; pos}))
      | A.SubscriptVar {var; exp; pos} ->
          let {exp=_; ty} = trvar var in
          check_int (trexp exp) ~pos;
          Type.if_array
            ty
            ~f:(fun ty_elements -> return ty_elements)
            ~otherwise:(fun () -> E.raise (E.Exp_not_an_array {ty; pos}))
      )
    and trop oper ~left ~right ~pos =
      let expty_left  = trexp left in
      let expty_right = trexp right in
      check_same expty_left expty_right ~pos;
      let {exp=_; ty} = expty_left in
      let module T = Type in
      (match oper with
      (* Arithmetic: int *)
      | A.PlusOp
      | A.MinusOp
      | A.TimesOp
      | A.DivideOp ->
          check_int expty_left ~pos;
          return_int
      (* Equality: int, string, array, record *)
      | A.EqOp
      | A.NeqOp ->
          if (T.is_int    ty)
          || (T.is_string ty)
          || (T.is_array  ty)
          || (T.is_record ty)
          then
            return ty
          else
            E.raise (E.Invalid_operand_type
              { oper
              ; valid = ["int"; "string"; "array"; "record"]
              ; given = ty
              ; pos
              })
      (* Order: int, string *)
      | A.LtOp
      | A.LeOp
      | A.GtOp
      | A.GeOp ->
          if (T.is_int    ty)
          || (T.is_string ty)
          then
            return ty
          else
            E.raise (E.Invalid_operand_type
              { oper
              ; valid = ["int"; "string"]
              ; given = ty
              ; pos
              })
      )
    in
    trexp exp
  and transDec ~env dec =
    (match dec with
    | A.VarDec {name; typ=typ_opt; init; pos=pos_outter; escape=_} ->
        let ty =
          (match (typ_opt, transExp ~env init) with
          | None, {ty; exp=()} ->
              ty
          | Some (sym, pos_inner), expty_init ->
              let ty = env_get_typ ~sym ~env ~pos:pos_inner in
              check_same {exp=(); ty} expty_init ~pos:pos_outter;
              ty
          )
        in
        Env.set_val env name (Value.Var {ty})
    | A.TypeDecs _ ->
        unimplemented ()
    | A.FunDecs _ ->
        unimplemented ()
    )

  let transVar ~env:_ var =
    (match var with
    | A.SimpleVar {symbol=_; _} ->
        unimplemented ()
    | A.FieldVar {var=_; symbol=_; _} ->
        unimplemented ()
    | A.SubscriptVar {var=_; exp=_; _} ->
        unimplemented ()
    )

  let transTy ~env:_ typ =
    (match typ with
    | A.NameTy {symbol = _; pos = _} ->
        unimplemented ()
    | A.RecordTy _ ->
        unimplemented ()
    | A.ArrayTy {symbol = _; pos = _} ->
        unimplemented ()
    )
end

open Semant

let transProg absyn =
  let {exp = _; ty = _} = transExp absyn ~env:Env.base in
  ()
Commit	Line	Data
523e2b06 SK	1	module List = ListLabels
523e2b06 SK	2
155ee327 SK	3	module A = Tiger_absyn
	4	module Env = Tiger_env
	5	module E = Tiger_error
155ee327 SK	6	module Translate = Tiger_translate
	7	module Type = Tiger_env_type
	8	module Value = Tiger_env_value
	9
	10	(* The only reason for having this seemingly-superfluous inner module is to
	11	* have this nice signature as a summary of what each function does. *)
	12	module Semant : sig
	13	type expty =
	14	{ exp : Translate.exp
	15	; ty : Type.t
	16	}
	17
	18	(* Violating normal naming convention just to make it easier to follow
	19	* Appel's
	20	*)
	21	val transExp : env:Env.t -> A.exp -> expty
	22	val transVar : env:Env.t -> A.var -> expty
	23	val transDec : env:Env.t -> A.dec -> Env.t
	24	val transTy : env:Env.t -> A.ty -> Type.t (* needs only type env *)
	25	end = struct
	26	type expty =
	27	{ exp : Translate.exp
	28	; ty : Type.t
	29	}
	30
	31	let unimplemented () =
	32	failwith "unimplemented"
	33
523e2b06 SK	34	let return ty = {exp = (); ty}
	35	let return_unit = return Type.Unit
	36	let return_nil = return Type.Nil
	37	let return_int = return Type.Int
	38	let return_string = return Type.String
155ee327	39
523e2b06 SK	40	let env_get_typ ~sym ~env ~pos : Type.t =
	41	match Env.get_typ env sym with
	42	\| Some ty -> ty
	43	\| None -> E.raise (E.Unknown_type {ty_id=sym; pos})
	44
	45	let env_get_val ~sym ~env ~pos : Value.t =
	46	match Env.get_val env sym with
	47	\| Some ty -> ty
	48	\| None -> E.raise (E.Unknown_id {id=sym; pos})
	49
	50	let check_same {exp=_; ty=ty_left} {exp=_; ty=ty_right} ~pos : unit =
	51	if Type.is_equal ty_left ty_right then
	52	()
	53	else
	54	E.raise (E.Wrong_type {expected=ty_left; given=ty_right; pos})
	55
	56	let check_int expty ~pos : unit =
	57	check_same {exp=(); ty=Type.Int} expty ~pos
	58
978cb41c SK	59	(* TODO: actual_ty *)
978cb41c SK	60
523e2b06 SK	61	let rec transExp ~env exp =
	62	let rec trexp exp =
	63	(match exp with
	64	\| A.NilExp ->
	65	return_nil
	66	\| A.IntExp _ ->
	67	return_int
	68	\| A.StringExp {string=_; _} ->
	69	return_string
978cb41c SK	70	\| A.CallExp {func; args; pos} ->
	71	(match env_get_val ~sym:func ~env ~pos with
	72	\| Value.Fun {formals; result} ->
	73	List.iter2 formals args ~f:(fun ty_expected exp_given ->
	74	check_same {exp=(); ty = ty_expected} (trexp exp_given) ~pos;
	75	);
	76	return result
	77	\| Value.Var _ ->
	78	E.raise (E.Id_not_a_function {id=func; pos})
	79	)
523e2b06 SK	80	\| A.OpExp {oper; left; right; pos} ->
523e2b06 SK	81	trop oper ~left ~right ~pos
0ed7a07c SK	82	\| A.RecordExp {fields=field_exps; typ; pos} ->
	83	let ty = env_get_typ ~sym:typ ~env ~pos in
	84	Type.if_record
	85	ty
	86	~f:(fun field_tys ->
	87	List.iter field_exps ~f:(fun (field, exp, pos) ->
	88	(match List.assoc_opt field field_tys with
	89	\| Some field_ty ->
	90	check_same {exp=(); ty=field_ty} (trexp exp) ~pos
	91	\| None ->
	92	E.raise
	93	(E.No_such_field_in_record {field; record=ty; pos})
	94	)
	95	)
	96	)
	97	~otherwise:(fun () ->
	98	E.raise (E.Wrong_type_used_as_record {ty_id=typ; ty; pos})
	99	);
	100	return ty
523e2b06 SK	101	\| A.SeqExp exps ->
	102	(* Ignoring value because we only care if a type-checking exception
	103	* is raised in one of trexp calls: *)
	104	List.iter exps ~f:(fun (exp, _) -> ignore (trexp exp));
	105	return_unit
	106	\| A.AssignExp {var; exp; pos} ->
	107	check_same (trvar var) (trexp exp) ~pos;
	108	(* TODO: Add var->exp to val env? *)
	109	return_unit
	110	\| A.IfExp {test; then'; else'; pos} ->
	111	(* test : must be int, because we have no bool *)
	112	(* then : must equal else *)
	113	(* else : must equal then or be None *)
	114	check_int (trexp test) ~pos;
	115	(match (trexp then', else') with
	116	\| expty_then, None ->
	117	expty_then
	118	\| expty_then, Some else' ->
	119	let expty_else = trexp else' in
	120	check_same expty_then expty_else ~pos;
	121	expty_then
	122	)
	123	\| A.WhileExp {test; body; pos} ->
	124	(* test : must be int, because we have no bool *)
	125	check_int (trexp test) ~pos;
	126	ignore (trexp body); (* Only care if a type-error is raised *)
	127	return_unit
	128	\| A.ForExp {var; lo; hi; body; pos; escape=_} ->
	129	check_int (trexp lo) ~pos;
	130	check_int (trexp hi) ~pos;
	131	(* Only care if a type-error is raised *)
	132	ignore (transExp ~env:(Env.set_typ env var Type.Int) body);
	133	return_unit
	134	\| A.BreakExp _ ->
	135	return_unit
8744eb3a SK	136	\| A.LetExp {decs; body; pos=_} ->
	137	(* (1) decs augment env *)
	138	(* (2) body checked against the new env *)
	139	let env =
	140	List.fold_left decs ~init:env ~f:(fun env dec -> transDec dec ~env)
	141	in
	142	transExp body ~env
4c550cd5 SK	143	\| A.ArrayExp {typ; size; init; pos} ->
	144	check_int (trexp size) ~pos;
	145	let ty = env_get_typ ~sym:typ ~env ~pos in
	146	Type.if_array
	147	ty
	148	~f:(fun ty_elements ->
	149	check_same {exp=(); ty=ty_elements} (trexp init) ~pos
	150	)
	151	~otherwise:(fun () ->
	152	E.raise (E.Wrong_type_used_as_array {ty_id=typ; ty; pos})
	153	);
	154	return ty
523e2b06 SK	155	\| A.VarExp var ->
	156	trvar var
	157	)
	158	and trvar =
	159	(function
	160	\| A.SimpleVar {symbol=sym; pos} ->
	161	(match env_get_val ~sym ~env ~pos with
	162	\| Value.Fun _ -> E.raise (E.Id_is_a_function {id=sym; pos})
	163	\| Value.Var {ty} -> return ty
	164	)
	165	\| A.FieldVar {var; symbol; pos} ->
	166	let {exp=_; ty} = trvar var in
	167	Type.if_record
	168	ty
	169	~f:(fun fields ->
	170	(match List.assoc_opt symbol fields with
	171	\| None ->
	172	E.raise
	173	(E.No_such_field_in_record {field=symbol; record=ty; pos})
	174	\| Some ty ->
	175	return ty
	176	)
	177	)
	178	~otherwise:(fun () -> E.raise (E.Exp_not_a_record {ty; pos}))
161a300d SK	179	\| A.SubscriptVar {var; exp; pos} ->
	180	let {exp=_; ty} = trvar var in
	181	check_int (trexp exp) ~pos;
	182	Type.if_array
	183	ty
	184	~f:(fun ty_elements -> return ty_elements)
	185	~otherwise:(fun () -> E.raise (E.Exp_not_an_array {ty; pos}))
523e2b06 SK	186	)
	187	and trop oper ~left ~right ~pos =
	188	let expty_left = trexp left in
	189	let expty_right = trexp right in
	190	check_same expty_left expty_right ~pos;
	191	let {exp=_; ty} = expty_left in
	192	let module T = Type in
	193	(match oper with
	194	(* Arithmetic: int *)
	195	\| A.PlusOp
	196	\| A.MinusOp
	197	\| A.TimesOp
	198	\| A.DivideOp ->
	199	check_int expty_left ~pos;
	200	return_int
	201	(* Equality: int, string, array, record *)
	202	\| A.EqOp
	203	\| A.NeqOp ->
	204	if (T.is_int ty)
	205	\|\| (T.is_string ty)
	206	\|\| (T.is_array ty)
	207	\|\| (T.is_record ty)
	208	then
	209	return ty
	210	else
	211	E.raise (E.Invalid_operand_type
	212	{ oper
	213	; valid = ["int"; "string"; "array"; "record"]
	214	; given = ty
	215	; pos
	216	})
	217	(* Order: int, string *)
	218	\| A.LtOp
	219	\| A.LeOp
	220	\| A.GtOp
	221	\| A.GeOp ->
	222	if (T.is_int ty)
	223	\|\| (T.is_string ty)
	224	then
	225	return ty
	226	else
	227	E.raise (E.Invalid_operand_type
	228	{ oper
	229	; valid = ["int"; "string"]
	230	; given = ty
	231	; pos
	232	})
	233	)
	234	in
	235	trexp exp
8744eb3a SK	236	and transDec ~env dec =
	237	(match dec with
	238	\| A.VarDec {name; typ=typ_opt; init; pos=pos_outter; escape=_} ->
	239	let ty =
	240	(match (typ_opt, transExp ~env init) with
	241	\| None, {ty; exp=()} ->
	242	ty
	243	\| Some (sym, pos_inner), expty_init ->
	244	let ty = env_get_typ ~sym ~env ~pos:pos_inner in
	245	check_same {exp=(); ty} expty_init ~pos:pos_outter;
	246	ty
	247	)
	248	in
	249	Env.set_val env name (Value.Var {ty})
	250	\| A.TypeDecs _ ->
	251	unimplemented ()
	252	\| A.FunDecs _ ->
	253	unimplemented ()
	254	)
155ee327 SK	255
	256	let transVar ~env:_ var =
	257	(match var with
	258	\| A.SimpleVar {symbol=_; _} ->
	259	unimplemented ()
	260	\| A.FieldVar {var=_; symbol=_; _} ->
	261	unimplemented ()
	262	\| A.SubscriptVar {var=_; exp=_; _} ->
	263	unimplemented ()
	264	)
	265
155ee327 SK	266	let transTy ~env:_ typ =
	267	(match typ with
	268	\| A.NameTy {symbol = _; pos = _} ->
	269	unimplemented ()
	270	\| A.RecordTy _ ->
	271	unimplemented ()
	272	\| A.ArrayTy {symbol = _; pos = _} ->
	273	unimplemented ()
	274	)
	275	end
	276
8744eb3a SK	277	open Semant
8744eb3a SK	278
155ee327	279	let transProg absyn =
155ee327 SK	280	let {exp = _; ty = _} = transExp absyn ~env:Env.base in
155ee327 SK	281	()